Note: Descriptions are shown in the official language in which they were submitted.
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ARTICLES, COMPOSITIONS, SYSTEMS, AND METHODS
USING SELECTIVELY DETACKIFIED ADHESIVES
REFERENCE TO RELATED APPLICATIONS
[0001] This applications claims priority to U.S. Provisional Patent
Application Serial Number
61/924,900, entitled Articles, Compositions, Systems, and Methods Using
Selectively Detackified
Adhesives, filed on January 8, 2014, and to U.S. Provisional Patent
Application Serial Number
62/063,131, entitled Articles, Compositions, Systems, and Methods Using
Selectively Detackified
Adhesives, filed on October 13, 2014, both of which are incorporated herein by
reference in their
entireties.
FIELD
[0002] The present subject matter relates to techniques for
detackifying an adhesive. These
techniques and associated aspects can be used in a wide range of applications
including selectively
deadening a region of adhesive. The present subject matter also provides
various processing equipment
to perform the adhesive deadening. In addition, the present subject matter
provides specific adhesive
compositions and articles containing the adhesive compositions.
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BACKGROUND
[0003] A wide range of applications and uses are known for relatively
thin labels or
laminates. Such "ultra thin" constructions as known in the industry offer
several benefits including
improved aesthetics and lower material cost as a result of a reduction in
thickness of one or more film
layers.
[0004] However, processing such ultra thin laminates can lead to a
variety of processing
difficulties. For example, such thin constructions may result in die cutting
issues and difficulties in
maintaining die strike lines. Furthermore, such thin constructions typically
exhibit less tensile strength
and thus may tear or fracture.
[0005] Besides processing ultra thin constructions, processing
difficulties may also arise
when die cutting labels or other laminates. Typically, labels are formed from
a continuous sheet of
adhesive backed facestock. Labels are formed by die cutting the facestock into
desired label shapes.
After die cutting, the portion of the facestock not used for labels (typically
referred to as "matrix") is
removed. Upon such removal, edge regions of the labels (typically referred to
as "label rims" or "rims")
are then exposed. A processing issue that can arise after die cutting adhesive
backed facestock or other
adhesive-containing laminates, e.g., labels, is "bleeding." Bleeding is a
phenomenon in which adhesive
flows outward from under a region of the cut facestock, laminate, or label
around the periphery or rim
of the cut article. The adhesive then typically contacts other processing
surfaces and can lead to a host
of problems.
[0006] Accordingly, a need exists for a strategy to avoid or at least
reduce the potential of
these various problems when processing labels, laminates and the like; and
particularly for thin
constructions.
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SUMMARY
[0007] The difficulties and drawbacks associated with previously known
practices and
technologies are addressed in the present articles, adhesive compositions,
systems, and methods.
[0008] In one aspect, the present subject matter provides a layered
assembly comprising a
face layer, a release layer, and a layer of adhesive disposed between the face
layer and the release layer.
Upon sufficient exposure to radiant energy, the exposed adhesive undergoes a
reduction in tack. At
least one of the face layer and the release layer is at least substantially
transparent to an extent such
that upon the exposure to radiant energy, the at least one of the face layer
and the release layer permit
radiant energy to pass therethrough to the adhesive.
[0009] In another aspect, the present subject matter provides an
adhesive composition
which upon sufficient exposure to radiant energy undergoes a reduction in
tack. The composition
comprises an effective amount of functionalized emulsion polymer.
[0010] In still another aspect, the present subject matter also
provides a method for
selectively reducing tack of an adhesive within a layered assembly. The method
comprises providing a
layered assembly including (i) a face layer, (ii) a release layer, and (iii) a
layer of adhesive disposed
between the face layer and the release layer. The adhesive has a
characteristic such that upon sufficient
exposure to radiant energy, the exposed adhesive undergoes a reduction in
tack. At least one of the
face layer and the release layer is substantially transparent to the radiant
energy. The method also
comprises irradiating the layered assembly with the radiant energy such that
the radiant energy passes
through at least one of the face layer and the release layer to the adhesive
layer. The irradiated
adhesive undergoes a reduction in tack.
[0011] In still another aspect, the present subject matter provides a
system for selectively
reducing tack of an adhesive within a layered assembly. The system comprises a
layered assembly. The
layered assembly includes (i) at least one of a face layer and a release layer
which is at least substantially
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transparent, and (ii) a layer of adhesive disposed adjacent to the at least
one face layer and the release
layer. The adhesive layer has a characteristic such that upon sufficient
exposure to radiant energy, the
exposed adhesive undergoes a reduction in tack. The system also comprises a
source of radiant energy.
The radiant energy is able to reduce tack of the adhesive in the layered
assembly.
[0012] In yet another aspect, the present subject matter provides a
method for allowing
relatively thin labels to be used in a label dispensing operation in which a
release liner is separated from
an adhesive face of the label and the label is applied to an article to be
labeled. The method comprises
prior to separating the release liner from the adhesive and label, irradiating
at least a portion of the
adhesive with radiant energy, whereby the irradiated adhesive undergoes a
reduction in tack and a
reduced peel force is obtained upon separating the release liner from the
adhesive and label.
[0013] In still a further aspect, the present subject matter provides
a layered adhesive
assembly comprising a face layer, a substrate, and an adhesive layer disposed
between the face layer
and the substrate. The adhesive undergoes a reduction in tack upon sufficient
exposure to radiant
energy. The adhesive layer includes a first zone of reduced adhesion, a second
zone of deadened
adhesion, and a third zone of non-reduced or non-deadened adhesion.
[0014] In yet another aspect, the present subject matter provides a
layered adhesive
assembly comprising a substrate, and an adhesive layer disposed on the
substrate. The adhesive
undergoes a reduction in tack upon sufficient exposure to radiant energy. The
adhesive assembly
defines an edge extending around the assembly and the adhesive layer includes
at least one zone of
reduced or deadened adhesion, and another zone of non-reduced or non-deadened
adhesion. The zone
of reduced or deadened adhesion is at least partially located between and
exclusively between the zone
of non-reduced or non-deadened adhesion and the edge.
[0015] In still a further aspect, the present subject matter provides
a method of promoting
adhesion between an adhesive article and a surface of interest and reducing
occurrence of air bubbles
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along an interface between the adhesive article and the surface of interest.
The method comprises
providing an adhesive article including a substrate and an adhesive layer
disposed on the substrate. The
adhesive article defines an edge extending around the article. The adhesive
undergoes a reduction in
tack upon sufficient exposure to radiant energy. The method also comprises
defining a first zone within
the adhesive layer of the article along at least a portion of the edge. The
method additionally comprises
defining a second zone within the adhesive layer of the article spaced from
the edge and located such
that the first zone is exclusively between the edge and the second zone. And,
the method also
comprises irradiating the first zone of adhesive with radiant energy, whereby
the irradiated adhesive
undergoes a reduction in tack.
[0016] In yet another aspect, the present subject matter provides a
method of facilitating
removal of an adhesive article from a surface to which the article is adhered.
The adhesive article
includes a substrate and an adhesive layer disposed on the substrate. The
adhesive article defines an
edge extending around the article. The adhesive undergoes a reduction in tack
upon sufficient exposure
to radiant energy. The method comprises defining a first zone within the
adhesive layer of the article
along at least a portion of the edge. The method also comprises defining a
second zone within the
adhesive layer of the article spaced from the edge. And, the method
additionally comprises irradiating
the first zone of adhesive with radiant energy, whereby the irradiated
adhesive undergoes a reduction in
tack.
[0017] In yet another aspect, the present subject matter provides a
method of producing
an adhesive assembly having at least one region of reduced adhesion. The
method comprises providing
an adhesive assembly comprising a facestock layer, an adhesive layer, and a
release liner. The adhesive
layer is disposed between the facestock layer and the release liner. The
adhesive undergoes a reduction
in tack upon sufficient exposure to radiant energy. The method also comprises
separating the release
liner from the adhesive assembly to thereby expose the adhesive layer. The
method additionally
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comprises irradiating at least a portion of the adhesive layer to thereby
produce at least one region of
reduced adhesion. And, the method also comprises recombining the previously
separated release liner
with the adhesive face of the irradiated adhesive layer, to thereby produce
the adhesive assembly.
[0018] In still another aspect, the present subject matter provides a
layered adhesive
assembly comprising a face layer defining an outer edge, and an adhesive layer
disposed on the face
layer. The adhesive undergoes a reduction in tack upon sufficient exposure to
radiant energy. The
adhesive layer defines one or more regions of deadened adhesive providing air
egress. The one or more
regions of deadened adhesive extend in a grid pattern in the adhesive layer.
The one or more regions of
deadened adhesive extend to the outer edge of the face layer.
[0019] In yet another aspect, the present subject matter provides a
method of reducing
occurrence of air bubbles along an interface between an adhesive label and a
container. The method
comprises providing an adhesive label including a face layer defining an outer
edge and an adhesive
layer disposed on the face layer. The adhesive undergoes a reduction in tack
upon sufficient exposure
to radiant energy. The adhesive layer defines one or more regions of deadened
adhesive providing air
egress. The one or more regions of deadened adhesive extend to the outer edge
of the face layer. The
method also comprises applying the adhesive label to a container by contacting
the adhesive layer to
the container, whereby air bubbles between the adhesive layer and the
container are displaced along
the regions of deadened adhesive toward the outer edge of the face layer.
[0020] In still another aspect, the present subject matter provides a
layered adhesive
assembly comprising a face layer defining an outer edge, and an adhesive layer
disposed on the face
layer. The adhesive undergoes a reduction in tack upon sufficient exposure to
radiant energy. The
adhesive layer defines one or more regions of deadened adhesive adjacent to at
least a portion of the
outer edge.
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[0021] In yet another aspect, the present subject matter provides a
labeled container
comprising a container defining an outer surface, and a layered adhesive
assembly disposed on and
contacting the outer surface of the container. The layered adhesive assembly
includes a face layer
defining an outer edge and an adhesive layer disposed between the face layer
and the outer surface of
the container. The adhesive undergoes a reduction in tack upon sufficient
exposure to radiant energy.
The adhesive layer defines one or more regions of deadened adhesive adjacent
to at least a portion of
the outer edge.
[0022] In still another aspect, the present subject matter provides a
layered adhesive
assembly comprising a face layer defining a plurality of panels and an outer
edge and at least one fold
line separating adjacent panels. The adhesive assembly also comprises an
adhesive layer disposed on
the face layer. The adhesive undergoes a reduction in tack upon sufficient
exposure to radiant energy.
The adhesive layer defines one or more regions of deadened adhesive. At least
one of the panels
includes a region of deadened adhesive.
[0023] In yet another aspect, the present subject matter provides a
labeled container
comprising a container defining an outer surface, and a layered adhesive
assembly disposed on and
contacting the outer surface of the container. The layered adhesive assembly
includes a face layer
defining an outer edge and at least one fold line separating adjacent panels,
and an adhesive layer. At
least a portion of the adhesive layer is disposed between at least one panel
of the face layer and the
outer surface of the container. The adhesive undergoes a reduction in tack
upon sufficient exposure to
radiant energy. The adhesive layer defines one or more regions of deadened
adhesive.
[0024] In still a further aspect, the present subject matter provides
a layered adhesive
assembly comprising a substrate and an adhesive layer disposed on the
substrate. The adhesive
undergoes a reduction in tack upon sufficient exposure to radiant energy. The
adhesive assembly
defines an edge extending around the assembly and the adhesive layer includes
at least one zone of
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fully deadened adhesion, at least one zone of non-reduced or non-deadened
adhesion, and at least one
zone of partially reduced adhesion.
[0025] In yet another aspect, the present subject matter provides a
container defining an
outer surface, and a layered adhesive assembly including a substrate and an
adhesive layer disposed on
the substrate. The adhesive undergoes a reduction in tack upon sufficient
exposure to radiant energy.
The adhesive assembly defines an edge extending around the assembly and the
adhesive layer includes
at least one zone of fully deadened adhesion, at least one zone of non-reduced
or non-deadened
adhesion, and at least one zone of partially reduced adhesion.
[0026] As will be realized, the subject matter described herein is
capable of other and
different embodiments and its several details are capable of modifications in
various respects, all
without departing from the claimed subject matter. Accordingly, the drawings
and description are to be
regarded as illustrative and not restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 is a schematic cross sectional view of an embodiment
of a layered assembly
in accordance with the present subject matter.
[0028] Figure 2 is a schematic perspective view of another embodiment
of a layered
assembly in accordance with the present subject matter.
[0029] Figure 3 is a graph showing reduction in tack of adhesive in
accordance with the
present subject matter.
[0030] Figure 4 is another graph showing reduction in tack of adhesive
in accordance with
the present subject matter.
[0031] Figure 5 is a schematic perspective view of a system for
selectively detackifying
regions of adhesive in a layered assembly in accordance with the present
subject matter.
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[0032] Figure 6 is a schematic perspective view of a layered assembly
having a select region
of detackified adhesive in accordance with the present subject matter.
[0033] Figure 7 is a schematic detailed cross sectional view of a
layered assembly having a
select region of detackified adhesive.
[0034] Figure 8 is a process schematic illustrating a system and
method in accordance with
the present subject matter.
[0035] Figure 9 is a schematic perspective view of a roller component
in accordance with
the present subject matter.
[0036] Figure 10 is another process schematic illustrating a system
and method in
accordance with the present subject matter.
[0037] Figure 11 is another process schematic illustrating a system
and method in which
peel force of certain regions of labels is reduced in accordance with the
present subject matter.
[0038] Figure 12 is a schematic view of a layered adhesive assembly
having multiple zones
of reduced adhesion in accordance with an embodiment of the present subject
matter.
[0039] Figure 13 is a schematic cross sectional view of the layered
adhesive assembly of
Figure 12.
[0040] Figure 14 is a schematic view of another layered adhesive
assembly having one or
more zones of reduced adhesion in accordance with an embodiment of the present
subject matter.
[0041] Figure 15 is a schematic cross sectional view of the layered
adhesive assembly of
Figure 14.
[0042] Figure 16 is a schematic perspective view of the adhesive
assembly of Figures 14-15
adhered to a surface.
[0043] Figure 17 is a schematic cross sectional view of the adhesive
assembly and surface
depicted in Figure 16.
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[0044] Figure 18 is a schematic cross sectional view of the adhesive
assembly of Figures 16-
17 during removal from the surface.
[0045] Figure 19 is a schematic illustration of a system and process
for delaminating,
selectively detackifying one or more regions of adhesive, and relaminating an
adhesive assembly in
accordance with an embodiment of the present subject matter.
[0046] Figure 20 is a perspective view of a label having a plurality
of air egress channels
formed along an adhesive face of the label in accordance with an embodiment of
the present subject
matter.
[0047] Figure 21 is a partial schematic view illustrating a portion of
the label of Figure 20.
[0048] Figure 22 is a detailed schematic view of a portion of the
adhesive face of the label
of Figure 20.
[0049] Figure 23 is a perspective view of a container and a label in
accordance with another
embodiment of the present subject matter.
[0050] Figure 24 is a view of an adhesive face of the label shown in
Figure 23.
[0051] Figure 25 is a perspective view of another container and a
label in accordance with
another embodiment of the present subject matter.
[0052] Figure 26 is a view of an adhesive face of the label shown in
Figure 25.
[0053] Figure 27 is a perspective view of still another container and
a label in accordance
with another embodiment of the present subject matter.
[0054] Figure 28 is a view of an adhesive face of the label shown in
Figure 27.
[0055] Figure 29 is a front view of another container and a label in
accordance with another
embodiment of the present subject matter.
[0056] Figure 30 is a front view of the label of Figure 29 partially
detached from the
container to reveal a rear face of the label.
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DETAILED DESCRIPTION OF THE EMBODIMENTS
[0057] The present subject matter relates to techniques of detackifying
or at least partially
deadening an adhesive layer using radiant energy such as UV light and/or
electron beam (periodically
referred to as "ebeam" energy). In certain embodiments, a layer of UV-
sensitive adhesive is exposed to
UV light for a certain time period to thereby detackify the adhesive. This
technique can be used in a
wide range of applications including selectively deadening a region of
adhesive such as along a matrix
stripping region. Doing so reduces the amount of delamination or separation
force, between adjoining
regions of a layered assembly, labels or other laminates, and thereby enables
the use of thinner
materials (among other advantages). The selected regions of adhesive layer(s)
can be detackified by
directing UV light through either or both of a face layer or a liner layer of
a layered assembly. The
present subject matter also includes directing radiant energy to exposed edge
regions of a laminate or
multilayer assembly. The present subject matter also provides various
processing equipment to perform
the adhesive deadening, such as a roller with a UV light included in the
roller. Other equipment,
methods, and applications are also contemplated pursuant to the present
subject matter. The present
subject matter also provides specific adhesive compositions that are sensitive
to radiant energy and
particularly UV-sensitive adhesive compositions. The adhesives can use certain
functionalized polymers
as described herein to provide a UV-sensitive emulsion pressure sensitive
adhesive (PSA). Sources of UV
light include high pressure, medium pressure, and low pressure mercury lamps,
optionally doped with
additives to adjust the emission spectrum, and LEDs emitting in the range 200-
400 nm. Other sources of
UV light are also suitable.
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ARTICLES
[0058] The articles of the present subject matter comprise one or more
layers such as a
substrate layer that defines a face, and one or more layers or regions of an
adhesive that is sensitive to
radiant energy as described herein. The term "sensitive to radiant energy" or
"UV-sensitive" or other
like term(s) refers to the adhesive having characteristics such that upon
exposure to certain forms of
radiant energy such as UV light for example, the adhesive undergoes a
reduction in tack level, as
typically evidenced as a reduction in its loop tack value. These aspects are
described in greater detail
herein.
[0059] In describing the extent of exposure to radiant energy, the term
"dose" can be used.
"Dose" refers to the total amount of applied energy. For ultraviolet light,
the units are of the form
"energy per area," for example, mJ/cm2 or kJ/m2. In electron beam curing, dose
is also a measure of
applied energy, but it is traditionally measured on a mass basis: J/kg, which
is called a "Gray," with
abbreviation Gy. In either case, dose is an important parameter. The dose is a
function of the intensity
of the UV or ebeam source, the relative transparency of any intervening
materials, and how long the
sample is exposed to the source. Higher intensity, higher transparency or
longer time means a higher
dose. In many applications, the adhesive is moved past a fixed energy source,
so that the speed of
motion determines the time under the source. In these cases faster speed
corresponds to lower dose.
If dose is held constant, the intensity of the energy source and the
corresponding time needed to apply
the dose matters, but this is a minor effect to that of the overall dose.
Typically the dose is applied all at
once by passing under a single energy source or in rapid succession by a
series of energy sources under
which the same passes, with the total exposure time measured in seconds or
fractions of seconds.
However, as long as the intensity during each exposure is above a certain
threshold, in principal the
dose can be applied in multiple exposures separated by minutes or even hours.
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[0060] UV exposure doses can be measured using a dosimeter such as the
UV Power Puck ll
from [IT LLC. The sensor of the dosimeter must be covered with a sample of the
at least partially
transparent layer to properly measure the UV dose actually delivered to the
adhesive layer. When
measured in this manner preferred doses are at least 500 mi/cm2 in a UV
wavelength range appropriate
to the one or more photoinitiators. More preferred are at least 250 mi/cm2 and
most preferred are at
least 150 mi/cm2.
[0061] In certain embodiments, the present subject matter provides
layered assemblies
comprising a face layer or other substrate, a release liner or "liner" layer,
and a layer of radiant energy
sensitive adhesive disposed between the face layer and the liner layer. Figure
1 schematically depicts a
layered assembly 10 comprising a face layer 20, a layer of radiant energy
sensitive adhesive 30, and a
liner layer 40. The face layer 20 defines oppositely directed faces 22 and 24.
And the liner layer 40
defines oppositely directed faces 42 and 44. It will be understood that the
layered assemblies of the
present subject matter including a layered assembly 10 may also include one or
more additional layers
or other components not shown in Figure 1.
[0062] In many embodiments and as described in greater detail herein,
one or more layers
for example two layers, in a layered assembly which are disposed immediately
adjacent to the adhesive
layer or region are at least partially transparent to the passage of radiant
energy. For example, referring
to the layered assembly 10 depicted in Figure 1, one or both of the face layer
20 and the liner 40 are at
least partially transparent such that the layer(s) allow UV light to pass
through the respective layer(s) to
the adhesive. The extent of transmittance of the UV light is such that the
adhesive undergoes a
reduction in tack level. These aspects are described in greater detail herein.
[0063] Figure 2 is a schematic perspective view of another layered
assembly in accordance
with the present subject matter. The layered assembly 100 comprises a face
layer, a liner layer, and a
layer of a radiant energy sensitive adhesive disposed between the face layer
and the liner layer. The
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present subject matter provides strategies for selectively detackifying one or
more regions of adhesive
by selectively exposing only those regions to the radiant energy of interest.
For example, referring to
Figure 2, the layered assembly 100 may include one or more regions at which it
is desirable to detackify
or at least partially deaden the adhesive in those regions and in only those
regions. For example, the
layered assembly 100 can include a perforation line 110. In certain
applications it may be desirable to
detackify or at least partially deaden the adhesive in a region 115 generally
encompassing the line 110.
In another example, the layered assembly 100 can include a die cut or kiss cut
line 120 that extends
through a face layer. A region 125 of detackified or deadened adhesive can be
readily provided that
encompasses the line 120. This practice can be used to prevent or at least
reduce the potential for
adhesive "bleeding" along "rims" or cut edges. It will be understood that the
present subject matter
includes a wide array of different configurations of layered assemblies having
one or more regions or
areas of detackified or at least partially deadened adhesive, and is not
limited in any manner to the
particular embodiments described herein or shown such as in Figure 2.
Furthermore, in many
embodiments, the adhesive region(s) or layer(s) to be detackified are located
within the interior of a
layered assembly and thus are bounded by other layers such as a face layer and
a liner. However, the
present subject matter also includes selectively detackifying adhesive
region(s) or area(s) that are
exposed and not covered by one or more layers. In addition, the present
subject matter also includes
selectively detackifying edge regions of the adhesives. For example, referring
to Figure 2, in certain
applications it may be desirable to detackify or at least partially deaden an
edge region 117 of the
layered assembly 100. This strategy may prevent or reduce adhesive bleeding.
[0064] The various articles and layered assemblies of the present
subject matter comprise
(i) one or more layers of a material that is sufficiently transparent to
permit the passage of select radiant
energy therethrough, and (ii) one or more layers of a radiant energy sensitive
adhesive as described
herein in greater detail.
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[0065] A wide array of materials can be used for the transparent or
substantially
transparent material. Nonlimiting examples of light transmissive polymeric
film materials include for
example cellulose acetate butyrate, cellulose acetate propionate, cellulose
triacetate, polyether sulfone,
polymethyl methacrylate, polyurethane, polyester, polycarbonate, polyvinyl
chloride, syndiotactic
polystyrene, cyclic olefin copolymers, polyethylene naphthalate, and
copolymers or blends based on
naphthalene dicarboxylic acids. Optionally, the film can contain suitable
mixtures or combinations of
these materials. In certain embodiments, a transparent face film of
polyethylene terephthalate (PET) or
biaxially oriented polypropylene (BOPP) is used. In certain embodiments, it
contemplated that glassine
paper may be used. Glassine is sufficiently transparent to be used as a
transparent backing material and
in certain situations offers advantages over PET. An example of a glassine
material is FASSON BG40 liner
commercially available from Avery Dennison.
[0066] The layer through which the radiant energy passes must have at
least some
transparency to the radiant energy. For materials or layers having relatively
low transparency, a more
intense energy source, longer exposure time, and/or slower line speed, or
combinations thereof could
be utilized. For example, if a layer under review only transmitted 50% of the
radiant energy, that
deficiency could be compensated for by doubling the intensity of the energy
source, or reducing the line
speed by a factor of 2, or by a combination of these techniques.
[0067] Provided at least one layer in the various articles and layered
assemblies of the
present subject matter is sufficiently transparent, other layers may
optionally be substantially opaque.
Non-limiting examples of substantially opaque layers would include papers,
inks, paints, and pigments,
cavitated films such as cavitated BOPP, metallic coatings and foils, and paper
or polymer films with
dispersed fillers or pigments.
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RADIANT ENERGY SENSITIVE COMPOSITIONS
[0068] The present subject matter provides adhesive compositions that
upon exposure to
certain forms of radiant energy, undergo a reduction in tack. In many
embodiments the adhesive
compositions are UV-sensitive adhesives and undergo a reduction in tack upon
exposure to UV
radiation. The present subject matter includes adhesive compositions that
undergo reductions in tack
upon exposure to other forms of radiant energy such as electron beam. In
particular embodiments, the
present subject matter provides emulsion pressure sensitive adhesive
compositions which have
properties that can be selectively adjusted after drying and film formation.
As described herein,
typically such adjustment is performed by exposure to radiation such as UV
light or from an electron
beam. In many embodiments of the present subject matter, the reduction in tack
is accomplished by
free-radical polymerization which crosslinks the polymer. This increases the
gel content which has the
effect of reducing tack.
[0069] The adhesive compositions generally comprise emulsion particles.
The polymers of
the present subject matter are prepared by treating an emulsion polymer which
includes carboxylic acid
functional monomers with an ethylenically unsaturated monomer including an
epoxy group in the
presence of a suitable catalyst.
[0070] Other methods of introducing ethylenic unsaturation into an
emulsion particle are
contemplated. For example, an ethylenically unsaturated isocyanate or
ethylenically unsaturated
anhydride in the presence of a suitable catalyst could be used to treat an
emulsion polymer which
includes hydroxyl functional monomers. Alternatively, a suitable catalyst
could be used to transesterify
a (meth)acrylic monomer with a vinyl alcohol or vinyl ester containing
polymer. Other methods on
introducing ehylenic unsaturation into an emulsion particle known to those of
skill in the art are also
contemplated in conjunction with the present invention.
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[0071] Suitable emulsion polymers can be prepared via many different
processes by one
skilled in the art, such as emulsion polymerization, multistage emulsion
polymerization, mini-emulsion
polymerization, or dispersion of an existing polymer in water.
[0072] Emulsions suitable for the present subject matter may have
particle sizes from 50
nm to 1000 nm. In certain embodiments, the particle sizes are from 75 to 700
nm. And, in still other
embodiments, the particle sizes are from 200 to 500 nm.
[0073] Emulsions suitable for the present subject matter should
exhibit pressure sensitive
adhesive behavior at the intended use temperature prior to cure. Pressure
sensitive adhesives are
generally defined as materials which exhibit permanent tack at the intended
use temperature. Pressure
sensitive adhesives originate from a film forming, elastomeric material which
combines a high level of
tack with an ability to quickly wet the surface to which it is applied.
Pressure sensitive adhesives provide
fast bonding at low to moderate pressure as a result of their flow
characteristics. Pressure sensitive
adhesives also exhibit sufficient cohesion and elasticity so that they can be
handled and removed from
smooth surfaces without leaving any residue.
[0074] Suitable polymers for the present subject matter will have
glass transition
temperatures which result in pressure sensitive adhesive behavior at the
intended application
temperature. It is well known in the art to control glass transition
temperature by for example
monomer selection, and/or proportions of monomers in copolymers.
[0075] Suitable carboxylic acid monomers for the present subject
matter include acrylic
acid, methacrylic acid, itaconic acid, citraconic acid, acryloxypropionic
acid, maleic acid,
methacryloxyisopropyl acid phthalate, methacryloxyethyl acid phthalate,
acryloxyisopropyl acid
phthalate and acryloxyethyl acid phthalate. Combinations of carboxylic acid
monomers may be used.
Suitable amounts of carboxylic acid monomers range from 1 to 20 percent based
on total monomer. In
certain embodiments, the amount of carboxylic acid monomers is within a range
of from 2 to 12
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percent. In particular embodiments, the amount of carboxylic acid monomers is
within a range of from
3 to 10 percent. Also contemplated are monomers which may be converted to
contain carboxylic acid
groups, such as anhydride monomers such as maleic anhydride or readily
hydrolyzed ester containing
monomers such as methyl acrylate.
[0076] Ethylenically unsaturated monomers containing epoxy groups
suitable for the
present subject matter include glycidyl methacrylate, glycidyl acrylate,
acrylated epoxidized soybean oil,
allyl glycidyl ether and 3,4-epoxycyclohexyl methyl methacrylate. Combinations
of epoxy functional
monomers may be used. Suitable amounts range from 0.1 to 2 equivalents of
epoxy to each equivalent
of carboxylic acid monomer. In particular embodiments, the amount of epoxy
functional monomers is
from 0.2 to 1.5 equivalents. In still other embodiments, the amount of epoxy
functional monomers is
from 0.5 to 1 equivalents.
[0077] Suitable catalysts include tetrabutyl ammonium hydroxide,
methyl tributyl
ammonium hydroxide, ammonium hydroxide, tetrabutyl ammonium chloride,
methyltributyl
ammonium chloride, triphenyl phosphine and chromium acetate. Other catalysts
suitable for reacting
epoxies and carboxylic acids may also be used, and combinations of catalysts
may be used.
[0078] It may be desirable to add an inhibitor to prevent
polymerization of the ethylenically
unsaturated epoxy functional monomer or premature cure of the resulting
functionalized latex. Suitable
inhibitors include hydroquinone, methoxyhydroquinone, butylated hydroxy
toluene, phenothiazine,
TEMPO and 4-hydroxy TEMPO (also known as "4HT"). Combinations of inhibitors
may be used. Suitable
inhibitor levels are 10 to 3000 ppm. In certain embodiments, the concentration
of inhibitors is 20 to
2000. In particular embodiments, the concentration of inhibitors is 50 to 1000
ppm.
[0079] The polymers of the present subject matter may be cured by free
radical
polymerization using methods well known to those skilled in the art. Suitable
methods include heating
in the presence of a thermal free radical initiator, exposing to
electromagnetic radiation in the presence
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of a photoinitiator, or exposure to an electron beam or gamma radiation. In
certain embodiments, the
polymers are cured by exposure to ultraviolet light or electron beam.
[0080]
Suitable photoinitiators for use with the present subject matter include
benzophenone and benzophenone derivatives, thioxanthone and thioxanthone
derivatives such as
isopropyl thioxanthone and chlorothioxanthone, aryl phosphine oxides such as
2,4,6-
trimethylbenzoyldiphenylphosphine oxide and phenyl bis(2,4,6-trimethylbenzoyI)-
phosphine oxide,
benzoin and benzoin derivatives, benzil ketals such as Irgacure 651,
acetophenone and acetophenone
derivatives such as Irgacure 184, Irgacure 369.
[0081]
For certain applications, it may be desirable to use a "polymeric"
photoinitiator with
sufficiently high molecular weight to minimize any material extracting into
for example food. Suitable
polymeric photoinitiators include Esacure One from Lamberti, Genopol TX-1,
Genopol AB-2, Genopol BP-
2 from Rahn and Omnipol BP Omnipol SZ, and Omnipol TX from IGM Resin.
[0082]
Other photoinitiators known to those skilled in the art are also suitable. It
is also
contemplated the mixtures of photoinitiators may be used.
[0083]
Although the present subject matter has been described in association with
emulsion pressure sensitive adhesives, it is contemplated that in certain
applications it may be possible
to use a hot melt pressure sensitive adhesive having suitable curing
characteristics. It is also
contemplated that pressure sensitive adhesives based upon solution polymers,
i.e., solution polymer
pressure sensitive adhesives, could also be used in accordance with the
present subject matter.
SYSTEMS AND METHODS
[0084]
The present subject matter also provides various methods of selectively
detackifying
one or more regions of adhesive and particularly region(s) of an adhesive
layer in a layered assembly. In
certain embodiments, the methods of the present subject matter utilize a mask
to selectively direct
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radiant energy to one or more regions of a layered assembly or at least
facilitate the formation of
detackified adhesive regions. Figures 5-7 schematically illustrate methods of,
and systems for,
selectively detackifying particular regions of an adhesive layer of a layered
assembly. Figure 5
schematically depicts a system 200 comprising a source 210 or emitter of
radiant energy 220, and a
mask 230. The system 200 can be used to selectively detackify region(s) of
adhesive within a layered
assembly such as 240. In certain embodiments, the system 200 may include the
layered assembly 240.
Specifically, the mask 230 defines one or more regions 235 that permit the
passage of radiant energy
220 from the radiant energy source 210. For example, the passage regions 235
defined in the mask 230
can be in the form of openings or apertures extending through the thickness of
the mask 230.
Alternatively, the passage regions 235 can be regions of material that permit
passage of the radiant
energy from one side or face of the mask 230 to the other side or face. The
remaining regions of the
mask excluding the passage regions 235 should block or at least substantially
block the radiant energy.
The mask is configured to prevent exposure or keep exposure from the UV light
or other radiant energy
below the threshold for tack reduction in regions of the layered assembly that
are not to be detackified.
[0085] Visual indication provisions can be included or otherwise
incorporated in the
layered assemblies to denote regions or areas of deactivation. For example, a
color indicator can be
used to denote regions or areas of a layered assembly that have been
deactivated or which are to be
deactivated. One or more color indicators can be in the form of pigments,
dyes, inks, or the like which
provide a visual indication. The color indicators can be incorporated into
particular layers, regions, or
components of the layered assemblies. Alternatively or in addition, the one or
more color indicators can
be applied or otherwise deposited on select areas or regions of the layered
assemblies. It will be
appreciated that the present subject matter is not limited to color indicators
as described. Instead, the
present subject matter includes any suitable means for denoting regions or
areas of deactivation.
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[0086] The system 200 is used to selectively detackify adhesive
region(s) within a layered
assembly by positioning the mask 230 between the source 210 of radiant energy
220 and the layered
assembly 240 such that upon emission of the radiant energy, e.g, UV light,
from the source 210, the
radiant energy passes through the passage regions 235 defined in the mask 230
and irradiates desired
region 245A of the layered assembly 240. The mask 230 prevents radiant energy
from irradiating other
regions of the layered assembly 240 besides the desired region 245A. Thus, the
mask 230 is described
herein as providing "exclusive irradiation" of one or more desired regions of
a layered assembly. As will
be understood, in many applications it is desirable to position the mask 230
relatively close to and in
certain embodiments immediately adjacent to, the layered assembly 240 to
reduce parallax error. And,
in particular embodiments of the present subject matter, the mask 230 is in
contact with the layered
assembly 240.
[0087] After exposure, i.e., irradiation, of the selected region 245A
of the layered assembly
240 to radiant energy 220 using the mask 230, a detackified region of adhesive
2453 is formed within
the layered assembly 240 as shown in Figures 6 and 7. Figure 7 is a detailed
schematic cross sectional
view of the layered assembly 240 taken across line VII-VII in Figure 6. Figure
7 schematically depicts the
detackified region 2453 of adhesive 260 disposed between and bounded by a face
layer 250 and a liner
layer 270. In performing the irradiation of the region 245A (see Figure 5) to
form the region 2453, the
radiant energy 220, e.g., UV light, may be directed to a face 252 of the face
layer 250 and/or to a face
272 of the liner layer 270.
[0088] Figure 8 schematically depicts another system 300 in accordance
with the present
subject matter. The system comprises a supply 310 of a layered assembly 320, a
station 330 at which
selective detackification is performed, and one or more processing units 340
such as a die cutter which
cuts or scores the layered assembly within regions which contain detackified
adhesive. More
specifically, representative operation of the system 300 is as follows.
Layered assembly 320 is supplied
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from a material source or supply 310 which may be in the form of a roll for
example. The layered
assembly 320 is generally as described herein and includes a layer or
regions(s) of a radiant energy
sensitive adhesive disposed between a face layer and a liner layer. The
layered assembly prior to
adhesive detackification is shown in Figure 8 as 320A. The layered assembly
320A is transferred from
the supply roll in the direction of arrow A towards the detackification
station 330. The station 330
generally includes a source of radiant energy and provisions for selectively
directing the radiant energy
to desired areas or regions of the layered assembly 320. In certain
embodiments, the provisions include
a mask such as described herein. The layered assembly 320A enters the station
330 and selective
detackification of certain adhesive regions is performed to thereby produce
the layered assembly 32013.
The layered assembly 32013 is then directed to one or more processing units
collectively shown in Figure
8 as 340. In certain embodiments, the processing units 340 are kiss cutting
units or other face layer
processing units. After passing through the processing unit(s) 340, the
processed layered assembly
shown in Figure 8 as 320C can be further processed such as passing through a
matrix stripping operation
in which waste matrix material is separated in the direction of arrow B from
remaining portions of the
layered assembly which may for example be transported in the direction of
arrow C.
[0089] The present subject matter also provides particular components
and/or equipment
for performing selective detackification of adhesive regions within a layered
assembly. Figure 9
schematically depicts a detackifying roller 400 in accordance with the present
subject matter. The roller
400 is in the form of a cylinder and defines an outer circumferential surface
420 that contacts the
layered assembly or other material to be selectively irradiated with radiant
energy. The roller 400 is
configured to rotate about an axis of rotation 410. The roller 400 also
comprises a source 440 of radiant
energy such as an emitter of UV light. The roller 400 also defines one or more
passage areas or regions
430 along the outer circumferential surface 420 that allow or permit the
passage of radiant energy from
the source 440 to the exterior of the roll 400. Thus, upon contact or
appropriate placement of a layered
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assembly to be detackified along the roll, radiant energy such as UV light
from the source 440 can pass
through select regions of the roller, i.e., the passage regions 430, to the
layered assembly and thereby
reach certain regions of adhesive within the layered assembly. It will be
understood that the present
subject matter includes a wide array of patterns, shapes, arrangements, and/or
configurations for the
passage regions 430. Thus, in no manner is the present subject matter limited
to the particular pattern
of the passage region 430 depicted in Figure 9.
[0090] In certain aspects of the present subject matter, and when
utilizing the roller 400 or
similar components, it may be desirable to provide drive controls or other
control provisions such that
the outer surface of the roller rotates in register control with a pattern
repeated on the layered
assembly, e.g., label. Insetting controls as known in the art can also be
utilized. Although the
embodiments described herein typically do not require focusing or
magnification of the irradiated
radiant energy, focusing and/or magnification provisions are included in the
present subject matter.
[0091] The detackifying rollers such as roller 400 can include
particular features such as the
use of a honeycomb grated surface. The outer roll surface may be covered with
flex plate or foil. For
example, it is contemplated that a template containing artwork or other
design(s) could be printed or
otherwise be formed and positioned about a roll to thereby constitute the
outer roll circumferential
surface. The diameter of the roll can be selected to match a particular print
or die size or an integer
number of label repeats.
[0092] Figure 10 schematically depicts another system 500 in
accordance with the present
subject matter. The system receives a source or supply (not shown) of a
layered material 510A which
includes a region of adhesive that is to be detackified. The layered material
510A is directed in the
direction of arrow D to a detackifying station 520 similar to the previously
described station 330 in
Figure 8. The detackifying station 520 emits radiant energy such as UV light
upon select regions of the
layered assembly to thereby reduce the adhesive tack in those regions and
thereby produce the layered
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material 51013 having one or more detackified regions. It will be understood
that the layered material
510A, 51013 can include print, text, or other indicia on one or more of its
faces or regions. The system
500 can optionally include provisions 525 for separating and/or removing one
or more layers such as a
release liner from the layered assembly. The removed layer may be collected on
a roller 530 or other
component.
[0093] After separation of a liner or other layer via the provisions
525, a remaining portion
510C of the layered assembly is directed to a vacuum roller 540. Prior to,
concurrently, or after contact
between the portion 510C and the roller 540, one or more regions of the
portion 510C may be further
exposed to radiant energy such as from a radiant energy source 550. The
radiant energy source 550
may be the same or different than the source of radiant energy utilized in the
detackifying station 520.
[0094] The vacuum roller 540 rotates about an axis 542 and includes
vacuum provisions
along certain regions of the outer surface of the roller that promote
engagement between the layered
portion 510C and the roller 540. As is known in the art, the vacuum provisions
typically include
apertures along the circumferential outer surface of the roller 540 which
expose the layered portion
510C (or other material layer or web) to reduced pressure which promotes
retention of the layered
portion 510C to the roller 540. Control provisions may be utilized to
selectively adjust or vary the
amount of circumferential surface region of the roller 540 along which the
vacuum provisions are
provided. Typically, in certain embodiments, the extent of surface region is
denoted by angle X, which
may be from about 30 to about 180 or more, and often about 90 . This
configuration is typically
referred to as a segmented vacuum roller.
[0095] The system 500 may also comprise a die cutter 560 or other
processing component
to directly apply cuts, scores, or perforations on the layered assembly 510C.
In many embodiments, the
cuts, scores, or perforations are located within a region of detackified
adhesive.
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[0096] The system 500 may additionally comprise separation provisions
570 for removing
one or more layers from the layered assembly 510C and/or relamination
provisions 572 for
incorporating one or more layers with the layered assembly 510C. The
separation provisions 570
remove one or more layers from the assembly 510C in the direction of arrow E.
The relamination
provisions 572 add or incorporate one or more layers with the assembly 510C in
the direction of arrow
F. Typically, in many embodiments, a die cutter is used to cut or form
multiple articles from the layered
assemblies 510C. The articles are then forwarded or otherwise positioned on a
transfer belt 580. The
speed of the transfer belt 580 is adjusted as desired. In certain embodiments,
the linear speed of the
transfer belt 580 is adjusted relative to the rotational speed of the roller
540 so as to create a spacing
between adjacent articles. The transfer belt 580 can include vacuum provisions
to promote retention of
articles on the belt 580. The transported articles such as cut labels, can be
further transported to
another process station in the direction of arrow G. For example, the cut
articles, e.g., labels, could be
transported to a label application station for subsequent attachment to
containers.
[0097] In certain applications, it may be necessary or at least
desirable to protect the
system, articles, and/or adhesive compositions from ambient UV light such as
that from sunlight.
However, the intensity of ambient UV is much lower than is typically used in
UV processing. Two factors
protect from unintended tack reduction under such weak exposures. One factor
is that oxygen inhibits
the tack reduction chemistry. Ambient air contains enough oxygen to suppress
the tack reduction until
a certain limiting light intensity is reached. While the detackifying
threshold depends on many factors,
in practice, sunlight is far below the threshold. Another factor relates to
use of a free-radical stabilizer
which can be added to the formulation which provides additional protection
from low level UV
exposure. Many such stabilizers are known in the art. An example of such is 4-
hydroxy TEMPO ("4HT"),
used at 200 to 2,000 ppm.
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[0098] The present subject matter includes numerous applications and
processing
techniques. For example, in one embodiment, by treating, i.e., exposure to
select radiant energy, matrix
areas of webs, the material properties of the matrix can be altered. This can
be used to allow or
promote easier removal of the matrix during a matrix stripping operation. This
strategy may be useful
when processing ultra thin constructions. Such altering of the material
properties include, but are not
limited to, reducing the release force and increasing mechanical properties of
the matrix. Furthermore,
in particular applications the face layer thickness can be reduced, thereby
reducing costs.
[0099] In another embodiment, a label surface may be treated, i.e.,
exposed to select
radiant energy, with the exception of an edge of the label. The treatment
reduces the peel force of the
label at a central or intermediate area, thus, promoting removal of the label
from a container after use
and once a corner of the label is lifted.
[00100] In another embodiment, a matrix is treated, i.e., exposed to
radiant energy, along
with a rim or edge portion of a label to prevent or at least reduce the
potential of bleeding.
[00101] In yet another embodiment, a layered assembly is provided having
multiple layers of
adhesive and particularly two layers of adhesive. One layer of adhesive is a
radiant energy sensitive
adhesive. The peel force associated with the layered assembly can be
selectively reduced by treating
the entire label, without such treatment being confined to specific label
areas. For example, a dual
adhesive layer having a UV-sensitive adhesive layer disposed as a face layer
or alongside a transparent
face film or label is provided at a coatweight of 13 g/m2. A second adhesive
layer is provided along the
UV-sensitive adhesive layer at a coatweight of 2 g/m2. Alternatively, the
second adhesive layer can be
applied upon a container or bottle. The film or label is applied to the
container and then treated, i.e.,
exposed to UV radiation, to deaden the UV-sensitive adhesive. This reduces the
effective adhesive to a
coatweight of 2 g/m2 after treatment.
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[00102] Another embodiment relates to forming a tray or container such
as by molding so as
to include a lid having a radiant energy sensitive adhesive layer that is
selectively deadened in areas at
which the container contents may contact the lid. The remaining portions of
the lid are not treated so
that those regions of the lid remain tacky and can seal or otherwise adhere
the lid to the container.
[00103] In another embodiment, a dual layer adhesive system is coated
such that a layer of
the radiant energy sensitive adhesive is along an outer or face side, dried,
and then treated on a
conventional lamination machine. The previous reference to "treated" refers to
exposing the radiant
energy sensitive adhesive to certain radiant energy to thereby detackify or at
least partially deaden that
adhesive layer. The material containing such adhesive layers could be self
wound. A self wound
material can be used to laminate a printed film, for example polypropylene
PP20 with reverse print on
an inside face. An advantage of the resulting construction as compared to
currently available materials
is that one film layer can be eliminated. An example of applications for such
labels and techniques
includes beer and beverage labels in which over-lamination as known in the art
is typical. The self
wound material may alternatively, be printable by itself.
[00104] In accordance with the present subject matter, the reduction in
adhesive tack can
be specified relative to the tack prior to exposure to radiant energy. The
present subject matter
includes a reduction in tack of from 1% to 99%. For many applications,
suitable reductions in tack are
greater than 30%. Typically, reductions in tack are greater than 50%. And in
certain embodiments,
reductions in tack are greater than 75%. In particular embodiments, reductions
in tack are greater than
90%. All of these tack reductions are relative to the initial tack of the
subject adhesive prior to exposure
to radiant energy. The minimum tack reduction will be a function of the
specific application, the
strength of the facestock used, and the starting tack of the adhesive. Tack
can be quantified using a
number of different tests or procedures. A typical method is Method PSTC-5
from "Test Methods for
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Pressure Sensitive Adhesive Tapes," 15th Edition, from the Pressure Sensitive
Tape Council. This method
is typically referred to as "Loop Tack" by those in the art.
[00105] The present subject matter can also be utilized to prevent or at
least reduce the
potential of adhesive bleeding. As previously described herein, after die
cutting adhesive laminates or
facestock, a common problem is adhesive bleeding along peripheral or rim
portions of the cut articles.
Use of the present subject matter in which edge or rim regions of adhesive are
selectively detackified
dramatically reduces their flow tendencies. Thus, by exposing cut edges of
labels for example to radiant
energy such as UV light as described herein, the potential for bleeding along
those regions can be
significantly reduced.
[00106] In yet another embodiment, aspects of the present subject matter
are utilized to
promote label dispensing and enable thinner face materials to be dispensed.
Generally, for applications
involving separation of a liner, backing, or other layer from an adhesive
label; by selectively detackifying
a leading edge of the label, a reduced peel force can be achieved upon
separation of the label from a
liner for example. Reduced peel forces can lead to decreased tearing or damage
of labels during
dispensing and may also enable the use of thinner labels or enable a wider
array of materials to be used
as labels.
[00107] Figure 11 is a process schematic illustrating a label having its
leading edge adhesion
reduced by selective detackification as described herein. Figure 11 also
illustrates conventional
dispensing of the same label without selective detackification. Specifically,
Figure 11 depicts a system
600 comprising a source of labels 605 with a release liner, provisions for
separating a label and a liner
such as a peel plate 610 typically used to facilitate separation of the liner
from the label, and provisions
615 for collecting the liner after separation from the label. Linered labels
which have been selectively
detackified are directed from the source 605 and directed to the peel plate
610 as shown by arrow A. It
is also contemplated that the label may be selectively detackified after
dispensing from the source 605.
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As a selectively detackified label passes over a distal edge 612 of the peel
plate 610, the liner is
transported in the direction of arrows B and C and subsequently collected at
615. The label(s) are
directed as shown by arrow D toward one or more articles to be labeled such as
a bottle 620.
[00108] Figure 11 also illustrates comparison of label dispensing and
application of
selectively detackified labels to label dispensing and application of
conventional labels. A conventional
label without selective detackification is shown passing from the peel plate
610 in the direction of arrow
E to an article to be labeled such as a bottle 625.
[00109] Selective detackification in accordance with the present
subject matter can be
performed upon one or more region(s) of labels from the source 605. In many
applications, selectively
detackifying a leading edge of a label prior to separation of a liner, such as
prior to the label reaching the
distal edge 612 of the peel plate 610 results in a reduced peel force along
the label leading edge,
thereby allowing thinner labels to be used.
[00110] In still another embodiment, aspects of the present subject
matter are utilized to
provide various layered adhesive assemblies in which one or more regions of an
adhesive are selectively
detackified as described herein. Figures 12-13 schematically illustrate a
layered adhesive assembly 700
which can for example be in the form of a coupon or other article having a
first region which is
separated from a remaining region and which such separation may be facilitated
by providing a pull tab
or other grasping member. The layered adhesive assembly 700 comprises a face
layer 705, a substrate
710, and a layer or region of adhesive 715 disposed therebetween. One or more
of these layers can be
transparent and/or substantially transparent. It will be understood that the
layered assembly 700 may
comprise additional layers, and in many applications will include print,
indicia, and/or other decorative
or informational items. One or more regions or portions of the adhesive 715
are irradiated as described
herein so as to reduce adhesion between the face layer 705 and the adhesive
715, and/or the substrate
710 and the adhesive 715. Figure 12 depicts a zone 720 having such reduced
adhesion. One or more
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lines or regions 730 can be formed or produced in the face layer 705 which may
facilitate separating the
portion of the layer 705 within the zone 720 of reduced adhesion from adjacent
or bordering portions of
the layer 705. The lines or regions 730 can be in the form of scores, cuts, or
other weakening of the face
layer 705. The lines or regions 730 generally extend around at least a portion
of the zone 720. The
layered assembly 700 can also include one or more regions or portions of the
adhesive 715 which are
irradiated as described herein so as to deaden adhesion, or substantially so,
between the face layer 705
and the adhesive 715, and/or the substrate 710 and the adhesive 715. Figure 12
further depicts a zone
725 having such deadened adhesion. One or more lines or regions 735 can be
formed or produced in
the face layer 705 which may facilitate separating the portion of the layer
705 within the zone 725 of
deadened adhesion from adjacent or bordering portions of the layer 705. The
line or region 735
generally extends around at least a portion of the zone 725. The lines or
regions 735 can be the same
as, or similar to, the previously described lines or regions 730. The zones of
differing adhesion, e.g.,
zones 720 and 725 can be contiguous or immediately adjacent to one another.
Alternatively, the zones
of differing adhesion can be separated by one or more regions of adhesive
which are not reduced or
deadened in their adhesiveness or tack. The region(s) of adhesive which are
not deadened or reduced in
adhesion may constitute a third type or class of zones. An example of the
adhesive assembly 700 is an
assembly of a coupon, e.g., 720, which can be easily torn or separated from a
carrier, e.g., 710, using a
pull tab, e.g., 725.
[00111] Figures 14-15 schematically depict another layered adhesive
assembly having one or
more zones of reduced or deadened adhesion in accordance with another
embodiment of the present
subject matter. Specifically, a layered adhesive assembly 750 comprises an
adhesive layer 755 and a
substrate 760. The assembly 750 may comprise one or more other layers. Any one
or more of the
layers can be transparent or substantially transparent. The adhesive assembly
750 includes one or more
zones 765 of adhesive which has not been reduced in its adhesiveness and at
least one other zone 770
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of reduced adhesion or deadened adhesive. The zones 765 and 770 are generally
separated by one or
more lines or regions 757. Generally, the non-reduced adhesion or non-deadened
zone(s) 765 is
centrally located or at least defined within an interior region of the
assembly 750 and thus is not
immediately adjacent to an edge 775. An example of the adhesive assembly 750
is a graphic article
having multiple regions of adhesive, e.g., non-deadened or non-reduced
adhesion zones 765, and one or
more peripheral edge regions of adhesive, e.g., 770, which have either been
reduced in adhesion or
deadened as described herein. Such adhesive articles may find wide application
as the area(s) of
reduced or deadened adhesiveness allow passage of air during application of
the article to a surface of
interest, i.e., contacting the adhesive layer, e.g., layer 755, to the
article. Such adhesive articles may
also find wide application because after their application, one or more
peripheral edge regions, e.g.,
regions 770 extending along edge 775, can be lifted from the surface to which
the article was applied to
thereby expose the adhesive regions, i.e., zone(s) 765, and facilitate
selective deadening of those
regions as described herein to promote removal of the adhesive assembly from
the surface.
[00112] Figures 16 and 17 schematically depict application of the
adhesive article 750 to a
surface 790. During and after application, i.e., contacting the adhesive layer
755 with the surface 790,
one or more air egress channels may result which promote and/or allow
expelling of air schematically
shown as arrows 780 along the interface between the adhesive layer 755 and the
surface 790.
Specifically, the one or more zone(s) 770 of reduced adhesiveness or deadened
adhesive extending
along edge 775 facilitate air egress. More specifically, in many embodiments,
the adhesive assembly
750 includes one or more zones of reduced or deadened adhesion which are at
least partially located
between and exclusively between the zone of non-reduced or non-deadened
adhesion, for example
zone 765, and the edge 775. And in particular embodiments, the zone(s) of
reduced or deadened
adhesion is immediately adjacent to the zone(s) of non-reduced or non-deadened
adhesion. In certain
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versions, the zone(s) of non-reduced or non-deadened adhesion is entirely
surrounded by the zone(s) of
reduced or deadened adhesion.
[00113] Referring further to Figure 16, the present subject matter also
provides methods of
promoting adhesion between an adhesive article and a surface of interest and
reducing occurrence of
air bubbles along an interface between the article and the surface. The method
comprises defining one
or more interior zones of adhesive spaced from an edge of the article and one
or more zones between
the edge and the interior zone(s) of adhesive. The zone(s) along the article
edge(s) is then irradiated to
selectively detackify the adhesive to reduce its adhesion or to deaden the
adhesive as described herein.
The area(s) in which the adhesive has been reduced in adhesion or deadened,
e.g., the edge zone(s),
permit air egress during and after application of the article to a surface.
Promotion of air egress reduces
the occurrence of air bubbles along the interface between the adhesive layer
and the surface.
[00114] Figure 18 schematically illustrates removal of the adhesive
article 750 which may for
example be a label, from the surface 790. In this removal technique, a portion
of the article 750 and
particularly a portion along edge 775, is pulled in the direction of arrow A
away from the surface 790 to
thereby expose at least a portion of the adhesive 765. The portion of adhesive
765 that is exposed is
exposed along an interface 766 generally defined between the adhesive 755 and
the surface 790. The
exposed adhesive 755 can then be irradiated as described herein to selectively
detackify and/or deaden
the adhesive to provide for easy removal of the article 750 from the surface
790.
[00115] The present subject matter includes exposing the adhesive to
radiant energy prior
to label application, during label application, after label application, or
any combination thereof. For
example, a label having adhesive as described herein which can be detackified
or deadened upon
sufficient exposure to radiant energy, can be applied to a surface of
interest. After application removal
of the label from the surface can be promoted by exposing the adhesive to
radiant energy. Such
exposure can be performed by directing radiant energy along the interface
between the label and the
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surface such as schematically depicted in Figure 18, and/or by directing
radiant energy through a front
substrate such as substrate 760, and/or by directing radiant energy through
the surface to which the
label is adhered, i.e., towards a rear face of the label.
[00116] The present subject matter includes variant configurations of
the layered adhesive
assembly such as the assembly 750 depicted in Figures 14-15. For example, the
zones 765 and 770
could be reversed such that zone 770 could include adhesive that has not been
reduced in adhesion or
deadened and zone 765 could include adhesive that has been reduced in adhesion
or deadened. Thus,
in such a variant embodiment, the layered adhesive assembly includes an
interior zone of low tack
adhesive which has been deadened or reduced in adhesion by exposure to radiant
energy, and an
exterior zone of high tack adhesive. In particular versions of this variant
embodiment, the high tack
zone surrounds the interior low tack zone, and the high tack zone may also
extend immediately adjacent
to an outer edge of the layered assembly. Such label configurations provide
easy and "clean" removal of
the label from a surface to which the label was previously applied.
[00117] Figure 19 schematically illustrates a system 800 and method for
performing one or
more delamination and relamination operations using an adhesive assembly
including a facestock layer,
a release liner, and an adhesive that undergoes a reduction in tack upon
sufficient exposure to radiant
energy. The system 800 comprises an inlet 805 at which an adhesive assembly is
provided. The
adhesive assembly is directed to delamination provisions 810 in which the
release liner is separated
from the adhesive layer. The resulting facestock layer having an exposed
adhesive face is directed to a
rotary mask 830, which can be for example in the form of the system described
in conjunction with
Figure 9 herein. The adhesive layer is then selectively irradiated with
sufficient radiant energy to
thereby selectively detackify one or more regions of the adhesive layer. After
selective detackification,
the adhesive assembly is directed to relamination provisions 840 at which the
facestock and selectively
detackified adhesive layer are combined with a release liner 850, and in many
applications, the same
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release liner that was previously delaminated at provisions 810. The produced
adhesive assembly can
be wound into a roll form.
[00118] The present subject matter also provides a variety of labels
uniquely suited for
particular applications. For example, the present subject matter can be used
to form one or more air
egress passages, regions, or channels along an adhesive face of a label. The
air egress regions can
extend across one or more portions of a label face, and typically extend from
an interior face region to
one or more edges. As will be appreciated, providing air egress regions
facilitates and promotes
removal of air from between the label and a surface to receive the label
during and after label
application. Removal of air bubbles, otherwise trapped between the label and
the surface, reduces the
occurrence of label blisters, visible air bubbles under the label, and other
label defects.
[00119] Figures 20-22 illustrate a label 900 in accordance with an
embodiment of the
present subject matter having one or more regions 905 for air egress. The
label comprises a label face
layer or substrate 920 having a layer of adhesive 910 as described herein.
Upon sufficient exposure to
radiant energy, the exposed adhesive undergoes a reduction in tack. And, upon
sufficient exposure to
radiant energy, the exposed adhesive becomes adhesively deadened. The air
egress regions or "lanes"
905 can be formed using a variety of techniques including for example, a mask
as shown in Figure 5 or a
detackifying roller as depicted in Figure 9. The air egress regions or lanes
905 extend to one or more
edges 902 of the label 900, and specifically to the outer edge(s) of the face
layer 920. The air egress
regions 905 can be formed in nearly any pattern such as a grid pattern
depicted in Figures 20 and 22.
However, the present subject matter includes forming the air egress regions in
non-uniform
arrangements. Typically, if the air egress regions 905 are formed in a grid
pattern, each region or lane
905 of deadened adhesive has a width such as w1 and/or w2 of from about 500
microns up to about
10,000 microns. However, it will be appreciated that the present subject
matter includes air egress
regions having widths less than 500 microns and/or greater than 10,000
microns. For patterns of air
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egress regions, such as a grid pattern depicted in the referenced figures, the
air egress regions 905 may
have multiple or different widths such as w1 being a first width and w2 being
a second width. In
particular applications, it may be beneficial to form air egress regions
having a relatively long length to
have a width greater than the width of air egress regions which are shorter in
length. Furthermore, if a
grid pattern is used, the grid pattern may be non-uniform such that the
spacing or distance between
adjacent air egress regions or lanes 905 is different at various locations
along the adhesive face. Upon
application of the adhesive label to a container, air bubbles between the
adhesive layer and the
container are displaced along the regions of deadened adhesive toward the
outer edge of the label.
Labels such as label 900 will find wide application and particularly for
freshly blown high density
polyethylene (HDPE) and polyethylene terephthalate (PET) bottles or
containers. Labels such as label
900 will also find wide application as pressure sensitive labels which exhibit
improved "wipedown" as a
result of increased air egress under the applied label. Furthermore, labels
such as label 900 will find
particular application where improved "laydown" and wet-out is desired, such
as for many labeling
applications involving clear containers.
[00120] Adhesive assemblies or labels described herein such as those
depicted in Figures 14-
18 and 20-22 can be used in various methods and techniques for reducing
occurrence of air bubbles
between a label and a surface to which the label is applied. Generally, the
methods involve providing a
label that includes one or more regions of adhesive as described herein, and
in which select regions of
the adhesive have been deadened or reduced in adhesion. In particular
embodiments, one or more air
egress regions such as channels 905 depicted in Figures 20 and 22 are formed.
The label is applied to
the surface and any air bubbles between the adhesive layer and the surface are
displaced along the
regions of deadened adhesive toward the outer edge of the label. In certain
applications, displacement
of air bubbles can be promoted by wiping the outer face of the label.
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[00121] The present subject matter also provides labels with one or
more adhesive regions
which have been exposed to radiant energy to thereby form region(s) of reduced
tack or deadened
adhesive. Incorporation of such aspects enable the use of non-traditional
labels such as labels which
extend outward from a container face, labels which can be folded outward from
a container surface,
and labels that can contain text, designs, and/or markings along a rear face
of the label for viewing.
Figures 23 and 24 depict a container A having an outer surface with a label
930 adhered thereto. The
label 930 defines an outer edge 931, a front face 932 and an oppositely
directed rear face 934. The label
930 includes a layer of adhesive as described herein along its rear face 934.
The adhesive is selectively
exposed to radiant energy to form one or more regions of deadened adhesive
such as region 937
adjacent the edge 931 or a portion thereof while leaving one or more regions
of non-deadened adhesive
936. The regions 936 and 937 are separated by a border 933 which may also
constitute a fold line for
the label. Thus for example, a lower region of the label 930 can be folded or
extended outward from
the container A to reveal a rear face of the label which can include
additional text, designs or the like.
The lower region 937 of deadened adhesive is defined along a lower edge
portion of the outer edge 931.
The present subject matter includes versions in which region(s) of deadened
adhesive extend along top
portions, side portions, bottom portions, or combinations thereof, of the
outer edge.
[00122] Figures 25-26 illustrate another embodiment of a label 940 and
container A. In this
version, a rear adhesive face of the label 940 is selectively deadened as
described herein to form an
upper region 946 adjacent an outer edge 941 in which the adhesive has been
deadened, and a lower
region 947 in which the adhesive has not been deadened or reduced in tack. The
label defines a front
face 942 and an opposite rear face 944. Upon application to the container A,
an upper region of the
label 940 may extend outward from the container A, and can in certain
instances, hang or be folded
downward to reveal a portion of the label rear face 944. The label can also be
adhered to a container
such that the upper, top region of the label containing one or more regions of
deadened adhesive
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extends above the container, and the lower region of the label containing
nondeadened adhesive is
used to adhere the label to the container. In many applications, the region(s)
of deadened adhesive can
also include text, indicia, designs or other markings. The regions 946 and 947
may be separated by a
border 943 and thus upon label application to the container A, the upper
portion of the label may be
folded or otherwise deformed along the border 943. The upper region 946 of
deadened adhesive is
defined along an upper edge of the outer edge 941. Labels such as labels 930
and 940 depicted in
Figures 23-26 can be used in various point-of-purchase (POP) applications.
Various point-of-purchase
labels are described in WO 2012/123814. The present subject matter includes a
wide array of labels and
is not limited to those described herein or shown in the noted figures. For
example, the present subject
matter includes labels which include lateral or side regions of deadened
adhesive.
[00123] The present subject matter also provides expanded content labels
([CL) in which
one or more region(s) of a label can be accessed to reveal additional label
region(s) that are covered or
not exposed when the label is in its initial applied configuration to a
container. In many applications, an
expanded content label includes one or more rear faces of the label which can
be accessed to reveal
additional text or information printed thereon. For example, Figures 27 and 28
illustrate a label 950
adhered to a container X. The label 950 defines a plurality of panels A-E
along one face, and another
plurality of panels F-J along another face. Panel A includes an adhesive as
described herein which is not
deadened, or may include a conventional adhesive. Generally, the label defines
one or more fold lines
that separate adjacent panels. In many embodiments, the panels can include
text, designs, and/or
indicia on one or more of the panels. And in certain label versions, the
various printing or markings are
provided on adjacent panels which are separated by a fold line. In certain
label versions, the one or
more regions of deadened adhesive are surrounded by non-deadened adhesive. The
label 950 is folded
such as Z-folded into a relatively flat configuration and adhered along panel
A to the container X. The
panel J is exposed along the outer surface of the container, and covers or
substantially covers all
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remaining panels of the label 950. The selective adhesive deadening techniques
and aspects described
herein can be used to form a region of deadened adhesive 954 defined within an
adhesive border 952,
within a panel C of the label; and another region of deadened adhesive 964
defined within an adhesive
border 962, within a panel E of the label 950. A tab 966 with non-deadened
adhesive can be included
with the label 950 such that upon folding the label, and adhering the label to
the container X along panel
A, the tab 966 is adhered to the container X to retain the label in its folded
configuration. As will be
appreciated, a consumer can access additional text and/or product information
on one or more of
panels G, B, C, H, I, and E by releasing the tab 966 and extending the label
950 from the container X.
[00124] Figures 29 and 30 illustrate another example of an expanded
content label in
accordance with another embodiment of the present subject matter. Figures 29
and 30 illustrate a label
970 adhered to container Y. The label 970 defines a front face 971, an
oppositely directed rear face 973,
and an outer edge 977. A layer of adhesive as described herein extends along
the rear face 973. Various
zones are defined along the adhesive layer and along the rear face 973 of the
label 970. A first zone 972
includes adhesive which has not been exposed to radiant energy and thus is not
reduced in adhesion or
deadened. A conventional adhesive can be used in the zone 972. A second zone
974 includes adhesive
which has been fully deadened or substantially so. Various text, indicia,
logos, and/or designs can be
provided within the second zone 974 along the rear face 973 of the label 970.
A third zone 976 includes
adhesive which has been partially reduced in adhesion to thereby provide a
removable bond upon
detachment from the container Y as shown in Figure 30. Thus, for label 970,
the zone 976 of reduced
adhesion extends immediately alongside the outer edge 977 and provides a
removable tab portion for
the label 970. As shown in Figure 30, the label 970 can be partially detached
from the container Y by
pulling the portion of the label at which zone 976 is located, away from the
container to thereby expose
or reveal the zone 974 along the rear face 973 of the label 970. It will be
understood that the present
subject matter includes a wide array of configurations of labels with various
arrangements and locations
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of zones of (i) reduced adhesion, (ii) completely deadened adhesive, and (iii)
non-reduced adhesion or
non-deadened adhesive. That is, in no way is the present subject matter
limited to any of the
representative embodiments described or shown herein.
EXAMPLES
Example 1: Evaluation of Adhesives
[00125] A series of investigations were performed to evaluate a
particular adhesive and its
ability to be selectively detackified by exposure to UV radiation.
Specifically, layered assemblies of face
stock, a release liner, and a layer of an adhesive disposed between the face
stock and the release liner
were prepared. UV radiation at various dosages was then directed through
either the face stock layer or
the liner layer to thereby detackify the adhesive. Layered assemblies in
accordance with the present
subject matter using a UV-sensitive adhesive were compared to corresponding
assemblies using an
adhesive not sensitive to UV radiation. Table 1 summarizes the layered
assemblies.
[00126] Table 1: Summary of Constructions of Samples 1-8
Sample Adhesive Face Stock Liner
1 UV-sensitive SC 56 gsm PET-23
2 Not UV-sensitive SC 56 gsm PET-23
3 UV-sensitive Metallized PET-23
4 Not UV-sensitive Metallized PET-23
UV-sensitive Vellum PET-23
6 Not UV-sensitive Vellum PET-23
7 UV-sensitive MC Prime Coat PET-23
8 Not UV-sensitive MC Prime Coat PET-23
[00127] The UV-sensitive adhesive used in Samples 1, 3, 5, and 7 was
prepared by a method
described in Example 2. Specifically, the method involved first building an
emulsion polymer of
composition 76% ethyl hexyl acrylate, 12% methyl methacrylate, 6% methyl
acrylate, 6% methacrylic
acid, 0.02% ethylene glycol dimethacrylate, and 0.02% n-dodecylmercaptan (76
EHA / 12 MMA / 6 MA!
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6 MAA / 0.02 EDGMA / 0.02 nDDM). This material was then treated with an
additional 3.5% GMA, using
a procedure similar to that taught in US 5,306,744. An effective amount of a
photoinitiator (a 50/50
mixture of bis(2,4,6-trimethylbenzoyI)-phenylphosphineoxide and 2-hydroxy-2-
methyl-1phenyl-propan-
1-one which is commercially available from Ciba Specialty Chemicals as DAROCUR
4265) is then added.
The other adhesive used in Samples 2, 4, 6, and 8 was 5692N available from
Avery Dennison. 5692N has
composition 81% ethyl hexyl acrylate, 12% methyl methacrylate, 6% methyl
acrylate, 1% acrylic acid,
0.4% ethylene glycol dimethacrylate, and 0.02% n-dodecylmercaptan (81 [HA / 12
MMA / 6 MA /1 AA /
0.4 EGDMA / 0.02 nDDM).
[00128] The PET-23 liner was polyethylene terephthalate (PET) film
having a thickness of 23
1-1m.
[00129] Face stock materials SC 56 gsm is available from FASSON and
metallized paper is
also available commercially.
[00130] The vellum face stock was noncoated paper grade.
[00131] MC Prime Coat is coated paper grade.
[00132] Referring to Figure 3, Samples 1 and 2 were exposed to
increasing dosages of UV
radiation. The adhesive layers of each sample were irradiated with UV
radiation that passed through
their liner layers. At designated intervals during such exposure, loop tack
measurements of the
irradiated adhesive faces were obtained. Dose in Figures 3 and 4 is calculated
using a lamp intensity in
W/m or W/inch and the speed of the moving web in m/s. 1 W/m equals 1 J/s.
Dividing the intensity
with the web speed results in J/m2 as the units for dose. As demonstrated in
Figure 3, Sample 1
exhibited a significant reduction in loop tack with increasing exposure to UV
radiation. In contrast,
Sample 2 exhibited a relatively constant loop tack value that did not
significantly change during
increasing exposure of UV radiation.
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[00133] Referring to Figure 4, regardless of whether UV radiation was
directed through a
PET-23 liner, vellum face stock, or MC Prime face stock, the samples utilizing
a UV-sensitive adhesive,
i.e., Samples 3, 5, and 7, all exhibited a significant reduction in loop tack
upon increasing exposure to UV
radiation. This behavior is significantly different than that of Samples 4,6,
and 8 which utilized an
adhesive that was not UV-sensitive.
[00134] Samples 1-4 (SC 56 gsm and metallized paper) demonstrate
exposure through the
PET-23 side. Both face stock materials (SC 56 gsm and metallized paper) have a
high optical opacity and
the UV light is blocked from the face stock side.
[00135] Samples 5-6 (vellum and MC Prime Coat) demonstrate exposure
through the paper
side (face stock) as the opacity is close to 80%.
[00136] In another evaluation, functionalization of an emulsion polymer
was investigated.
Example 2: Functionalization of Emulsion Polymer
[00137] 611 g of an emulsion polymer with composition 76 [HA! 12 MMA /
6 MA! 6 MAA /
0.02 EGDMA / 0.02 nDDM with particle size 350 nm and 57% solids was introduced
into a resin kettle
fitted with a reflux condenser and mechanical stirrer. 3.12 g of 19% ammonia
in water was added (0.15
equivalents, based on MAA), followed by 8.22 g of 55% tetrabutylammonium
hydroxide in water (0.075
equivalents based on MAA). The mixture was stirred and heated to 80 C.
[00138] A solution of 0.35 g 4-hydroxy TEMPO in 21.5 g glycidyl
methacrylate (6.4% based
on polymer, 0.65 equivalents based on MAA) was added to the heated mixture
over a 15 minute period.
The mixture was stirred at 80 C for four hours, then cooled to room
temperature.
[00139] Many other benefits will no doubt become apparent from future
application and
development of this technology.
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[00140] All patents, published applications, and articles noted herein
are hereby
incorporated by reference in their entirety.
[00141] As described hereinabove, the present subject matter solves
many problems
associated with previous strategies, systems and/or devices. However, it will
be appreciated that
various changes in the details, materials and arrangements of components,
which have been herein
described and illustrated in order to explain the nature of the present
subject matter, may be made by
those skilled in the art without departing from the principle and scope of the
claimed subject matter, as
expressed in the appended claims.
